Characterization of Bi4Ge3O12 single crystal by impedance spectroscopy

Abstract

Bi 4 Ge 3 O 12 (bismuth germanate -BGO) single crystals were produced by the Czochralski technique and their electrical and dielectric properties were investigated by impedance spectroscopy. The isothermal ac measurements were performed for temperatures from room temperature up to 750 °C, but only the data taken above 500 °C presented a complete semicircle in the complex impedance diagrams. Experimental data were fitted to a parallel RC equivalent circuit, and the electrical conductivity was obtained from the resistivity values. Conductivity values from 5.4 × 10 -9 to 4.3 × 10 -7 S/cm were found in the temperature range of 500 to 750 °C. This electrical conductivity is thermally activated, following the Arrhenius law with an apparent activation energy of (1.41 ± 0.04) eV. The dielectric properties of BGO single crystal were also studied for the same temperature interval. Permittivity values of 20 ± 2 for frequencies higher than 10 3 Hz and a low-frequency dispersion were observed. Both electric and dielectric behavior of BGO are typical of systems in which the conduction mechanism dominates the dielectric response.

X-ray excited luminescence and photoluminescence of Bi4(GeO4)3 glass-ceramics

“…All these TL peaks also follow second order kinetics. Macedo (Macedo et al, 2003) have measured the impedance of BGO crystals at high temperatures and frequencies and, using the Arrhenius law, calculated the activation energy of the thermal processes, to be 1.41 eV. This energy was associated with the deeper traps and the mechanism of conduction is due to hopping electrons released from these traps via the band gap which is 5 eV at room temperature (Barnes et al, 1984).…”

Optical properties of pure and Cr3+ doped BGO ceramic scintillators

“…The structural analysis of the calcined powders and sintered ceramics was done by X-ray diffraction (Rigaku DMAX 2000/PC) using Cu Kα radiation in continuous scanning mode, with a scanning speed of 2°/min in the 2θ range from 10° to 80°. All these steps in sample preparation were carried out following the same procedure as in previous papers [3,7,8] where all aspects were discussed in detail. Before the luminescence characterisation, the opaque ceramic disks were polished to a thickness of ~ 0.4 mm with silicon carbide and alumina powder.…”

“…Due to the difficulty in producing good quality, large samples, there is a motivation for finding ceramic materials which can be used in scintillator applications in place of single crystals [3,4]. The growth of BGO single crystals is widely reported in the literature [5][6][7] but there are only a few references on the synthesis of BGO ceramics [3,8].…”

Characterization of BGO glass–ceramic materials

“…Bismuth germanate (Bi 4 Ge 3 O 12 -BGO), which has a cubic crystalline structure known as eulityte, has been demanded a great deal of interest due to its electro-optic, electro-mechanical and scintillation properties [8,9]. The photo and radioluminescence excited with U.V.…”